Add layout manager to recyclerView

 <androidx.recyclerview.widget.RecyclerView
            android_id="@+id/gv_attach_image"
            android_layout_width="match_parent"
            android_layout_height="wrap_content"
            android_layout_marginStart="8dp"
            android_layout_marginTop="16dp"
            android_layout_marginEnd="8dp"
            app_layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
            android_nestedScrollingEnabled="true"
            android_visibility="gone" />

And connect your adapter to recyclerView

attachImageGV.setAdapter(galleryAdapter)

I wrote a image attaching code as shown below:
Recycler view:

<androidx.recyclerview.widget.RecyclerView
                            android_id="@+id/gv_attach_image"
                            android_layout_width="0dp"
                            android_layout_height="wrap_content"
                            android_layout_marginStart="8dp"
                            android_layout_marginTop="16dp"
                            android_layout_marginEnd="8dp"
                            android_nestedScrollingEnabled="true"
                            android_numColumns="3"
                            android_visibility="gone" />  

My Java code:

RecyclerView attachImageGV;
GalleryRecycleViewAdapter galleryAdapter;
@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        try {
            if (resultCode == RESULT_OK) {
                if (requestCode == PICK_FROM_GALLERY && data != null) {
                    String[] strings = {MediaStore.Images.Media.DATA};
                    imageEncodeList = new ArrayList<>();
                    ArrayList<Uri> uris = new ArrayList<>();
                    attachImageGV.setVisibility(View.VISIBLE);
                    if (data.getData() != null) {
                        Uri uri = data.getData();
                        String selectedFilePath = FilePath.getPath(mContext, uri);
                        imageEncodeList.add(selectedFilePath);
                        // Cursor cursor = mContext.getContentResolver().query(uri, strings, null, null, null);
                        //  cursor.moveToFirst();
                        //  int columnIndex = cursor.getColumnIndex(strings[0]);
                        //  imageEncoded = cursor.getString(columnIndex);
                        //  cursor.close();

                        uris.add(uri);
                        galleryAdapter.addImage(uri);


                    } else {
                        if (data.getClipData() != null) {
                            ClipData clipData = data.getClipData();
                            for (int i = 0; i < clipData.getItemCount(); i++) {
                                ClipData.Item item = clipData.getItemAt(i);
                                Uri uri = item.getUri();
                                String selectedFilePath = FilePath.getPath(mContext, uri);
                                //Cursor cursor = mContext.getContentResolver().query(uri, strings, null, null, null);
                                //  cursor.moveToFirst();
                                //   int columnIndex = cursor.getColumnIndex(strings[0]);
                                //   imageEncoded = cursor.getString(columnIndex);
                                imageEncodeList.add(selectedFilePath);
                                // cursor.close();

                                uris.add(uri);
                                galleryAdapter.addImage(uri);
                            }
                            Log.d("Report issue", "onActivityResult: Number of Selected Images" + imageEncodeList.size());
                        }
                    }
                } else {
                    Toast.makeText(mContext, "You've not attached any image!", Toast.LENGTH_LONG).show();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            Log.e(TAG, "onActivityResult, error is: ", e);
            Toast.makeText(mContext, "Something went wrong", Toast.LENGTH_SHORT).show();
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

Gallery adapter:

class GalleryRecycleViewAdapter : RecyclerView.Adapter<GalleryRecycleViewAdapter.ViewHolder> {
    var mContext: Context
    var mArrayList = ArrayList<Uri>()
    lateinit var onItemClickListener: OnItemClickListener

    //Below we are limiting the number of items on home screen
    private var limit = 0

    constructor(context: Context, onItemClickListener: OnItemClickListener) {
        this.mContext = context
        this.onItemClickListener = onItemClickListener;

    }

    constructor(context: Context) {
        this.mContext = context
    }


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {

        val binding = DataBindingUtil.inflate<GalleryviewerBinding>(LayoutInflater.from(parent.context),
                R.layout.galleryviewer, parent, false)
        return ViewHolder(binding)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.binding.ivGallery.setImageURI(mArrayList.get(position));

        holder.binding.ivRemoveAttach.setOnClickListener {
            mArrayList.removeAt(position)
            notifyDataSetChanged()

        }
    }

    override fun getItemCount(): Int {
        /*       return if (mArrayList != null) {
                   if (limit > 0) {
                       if (mArrayList.size > limit) {
                           limit
                       } else {
                           mArrayList.size
                       }
                   } else {
                       mArrayList.size
                   }
               } else 0*/
        return mArrayList.size

    }


    fun addImage(uri: Uri) {
        this.mArrayList.add(uri)
        notifyDataSetChanged()
    }

    inner class ViewHolder(internal var binding: GalleryviewerBinding) : RecyclerView.ViewHolder(binding.root)

    companion object {
        private val TAG = "EventsRecyclerViewAdapt"
    }

    fun getMarrayList(): ArrayList<Uri> {
        return mArrayList
    }
}

What am I missing?